engine oil wt. and zddp for 1966 428 Bird.

[mr4speed]

What wt. engine oil do you fellas use on a 1966 428 engine? I am currently using 10W30 with ZDDP in it plus I add a small bottle more. No leaks or burning oil. Do you think I could switch to synthetic of 20W30 or 40 and still use some ZDDP without harm to the engine. I use synthetic in my newer cars and I love it.

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[Ward 57]

I'm no expert and I have no problem with synthetics. But just be careful when changing out. They react differently with natural oils. After changing out I would suggest a high efficient oil filter change every 500 miles to catching any residual gunk. They have excellent lubricate efficiency But I don't know if they have the cushioning of classic oils. I'd go with a thicker blend like the 40. Couldn't do any harm.

 

[mr4speed]

I'm no expert and I have no problem with synthetics. But just be careful when changing out. They react differently with natural oils. After changing out I would suggest a high efficient oil filter change every 500 miles to catching any residual gunk. They have excellent lubricate efficiency But I don't know if they have the cushioning of classic oils. I'd go with a thicker blend like the 40. Couldn't do any harm.

Appreciate your reply

 

[64ZCODE]

I run Mobil 1 15W/50 full synthetic in my '64. It has ZDDP and I like the higher viscosity when hot because these older engines have larger clearances, especially as they wear.

And yes to using full synthetic oil, it lubricates better than non-synthetic oil. Years ago, Mustangs and 5.0 magazine did before and after dyno tests on a '90 Mustang with a 302. After switching to synthetic, the engine produced an additional 5 hp at the rear wheels, indicating less frictional drag on the rotating engine parts.